The Department of Energy (DOE) released a renewable-energy resource assessment detailing the potential to develop electric power generation at existing U.S. dams that aren’t currently equipped to produce power. The report estimates that, without building a single new dam, these available hydropower resources, if fully developed, could provide an extra electrical generating capacity of more than 12 gigawatts (GW), equivalent to roughly 15 percent of current U.S. hydropower capacity.

The report, “An Assessment of Energy Potential at Non-Powered Dams in the United States,” analyzes more than 54,000 specific sites that could be developed to generate power. The results indicate that, if fully developed, the nation’s nonpowered dams could provide enough energy to power more than 4 million households.

The greatest hydropower resource potential was found at lock and dam facilities on the Ohio, Mississippi, Alabama and Arkansas rivers—facilities owned by the U.S. Army Corps of Engineers. The top 10 sites alone have the potential to provide approximately 3 GW of generating capacity, while the top 100 sites together could potentially provide 8 GW of clean, reliable energy. Many of these dams could also likely be converted to power-generating facilities with minimal effect on critical species, habitats, parks or wilderness areas.

The resource assessment also finds many potential hydropower sites are located in areas with fewer wind or solar resources, giving nearby communities a way to secure renewable energy for local families and businesses. And because hydropower provides reliable baseload power day and night, developing existing dams could also provide flexibility and diversity to the electric grid and allow utilities to integrate other renewable-energy sources.

This report, funded by the DOE’s Office of Energy Efficiency and Renewable Energy, is intended to be a tool for state and local officials and industry stakeholders, and it will likely help bolster activity in hydropower deployment as the country seeks to generate more energy through renewables.